Industrial furnace and the like



Feb. 14, 1939. w. LENDER INDUSTRIAL FURNACE AND THE LIKE Filed Dec. 16,1956 3 Sheets-Sheet l 4 m mm f 6 /L 9 E 6 E9 7 711/ 7 m r HP J mm 4 LFeb. 14, 1939 w. LINDER 2,146,751 INDUSTRIAL FURNACE AND TEE LIKE FiledDec: l6, 1936 '3 Sheet-Sheet 2 c sf Feb. 14, 1939. w. LINDER INDUSTRIALFURNACE AND THE LIKE Filed Dec. 16, 1936 3 Sheets-Shget 5 to the middleaxis as the angle of the Patented Feb. 14, 1939 UNITED STATES PATENTOFFICE Application December 16, 1936,.Serial No.

In Germany December 17, 1935 6 Claims.

My invention relates to industrial furnaces, operating on hightemperatures, such as openhearth furnaces, electrically heated furnacesor the like, and more particularly to those furnaces provided with anarch-like roof built of individual bricks made of refractory material,for instance magnesite bricks and chromium magnesite bricks, heldtogether by an outer anchorage.

The main object of my invention consists in the provision of suchimprovements in said furnaces, by which the life and the resistance ofthe furnace roof is considerably increased.

It is well known that the arch-like roofs of open-hearth furnaces andsimilar furnaces soon show, after a comparatively short operating time,considerable damage, resulting from the expansion of the refractorymaterial which takes place under heat when the oven brickwork is heatedup to the operating temperature. On account of the heat expansion of theindividual bricks, the top or roof as a whole tends to expand.Furthermore-as the oven roof is heated only from the underside. whilstthe upper side is more or less cooled down by the comparatively coldatmosphere, the heat expansion in various zones of the roof brickworkwill vary quite considerably. Therefore, the shape of the roof arch willalter, following the alteration of the angle of the center of the archas well as the radius of the arch. On

account of the heat expansion, the arch bricks between the abutmentswill be subjected to an increased pressure throughout the whole sectionor in individual zones, so that the bricks will crack or deform,resulting finally in a collapse of the arch.

My present invention consists principally in suspending the arch roofbetween the abutments in such a manner, that the bricks can expand orcontract freely without loosening their connection. For this purpose, Iarrange to provide the said abutments so as to be moved transversely ofthe roof and also so as to be swung or movably turned in such a way,that the distance of the individual abutments,- as well abutments to thehorizontal, can be adjusted for every operating condition exactlyaccording to the position of the end bricks of the arch. Another featureof my invention consists in that, under certain circumstances, theabutments are not only movable in one direction, but are arranged to bemoved in all directions. thus for instance rendering it possible tosupport conical as distinguished from rectilinear arches in a mostsuitable way.

Furthermore, my invention provides for a new arch,

design of abutments, in that the abutments are mounted on levers, whichlevers are supported for movement, and have the abutments arranged atsuch a distance from the axis of the lever that, by swinging the levers,the distance of the abut- 5 ments from each other and the inclination ofthe abutments may be set according to the angularity of the center aswell as the length of the arch as a result of the alteration in'theradius of curve.- ture of the arch.

This feature may be adopted according to my invention especially toarches made of magnesite and chromium magnesite bricks, or bricks ofother suitable material.

Finally, another important object of this in- 15 vention consists in theprovision for acting on the abutments by means of springs in such a way,that the position of the abutments will adjust itself automatically tothe altered shape of the arch, with regard to the center as well as alsoto the altered length of the arch as a result of the altering of theradius of curvature of the arch.

Further objects of my invention may beseen from the followingdescription of a preferred embodiment of my invention.

Figure 1 of the drawings shows an industrial furnace designed accordingto my invention.

The left half of Figure 1 shows the arch roof in cold condition and theright half shows the 3 arch roof in hot condition.

Figure 2 is a side view of one section of the furnace, according toFigure 1.

Figure 3 shows on an enlarged scale a vertical section through theabutment spring Figure 4 is a horizontal section of Fig. 3 on lineFigure 5 shows on an enlarged scale avertical section through anabutment lever for a conical Figure 6 is a top view of the abutments ofthe arch according to Figure 5.

Figure 7 finally shows anabutment plateof the apparatus according toFigures 5 and 6.

The furnace according to Figures 1 and 2 consists of chamber l, formedby the bottom 2 and side walls 3, both being made of refractorymaterial. The bottom and side walls are held in position by an anchorageconsisting of vertical buckstays 4, the lower tie rods connecting bars6. The vertical moreover interconnected by the ers I.

The oven roof is formed by an arch 8, consisting of refractory bricksand covered outside buckstays 4 are horizontal girdaltered angularity ofthe 20 5 and the upper 60,

' abutment plate by a suitable heat insulating layer 3. The end bricksof the arch 3 are supported in abutments I3, whose lower projection IIis provided in such a manner that the end bricks of the arch cannotslide from the plate-shaped abutment Ill. The

l3 preferably extends over a multitude of arch bricks, as may be seenfrom Figure 2.

The abutment plate ill is mounted on angle levers l2 arranged formovement on the vertical buckstays] in bearings l3. A tension rod l1acts upon the lever arm M by means of set screws l5 and a ball-likepressure plate l6. Said tension rod I1 is pulled upwards by springsarranged in the casing waus l3 and [3.

Figure 3 shows the interior of the spring casing. The casing consists oftwo sections l3 and I9, which may be moved telescopically. The casingsection l9, as shown in Figure 1, is movably supported on bearings 20,arranged on the connecting bars 6. The casing section l9 isprovided witha central bore 2|, through which extends the spring tension rod IT. Thethreaded end 22 of the tension rod ll reaches outwards through asuitable bore of the casing section l3 and carries the set screws 23.

The portion of the spring tension rodl1 inside the casing is surroundedby a number of spiral springs 24. concentrically to each spring isarranged a connecting pin 25, the head 23 of which fits against thebottom of the casing section IS. A nut 21 bolted on the upper threadedend of the pin 25 rests against the upper side of the casing l3. Thesprings 24 are held in position by the projections 28 and 23, providedin the lower casing section l3 and in the upper casing section l3. Thefinal coils of the spiral springs surround these projections.

Figure 1 shows the arch as being arranged at a certain distance from thetopmost layer of the oven sidewall 3. In order to protect the abutmentIll, consisting of a suitable metal, against the influence of the oven-heat, protection bricks 30 or a sand seal have been arranged on thetopmost layer of the side walls. Said protection bricks are suitablymovable, so that they may be adjusted corresponding to the resultingmovement of the arch when the same is heated up to the operatingtemperature, whereby the space between the arch and the oven sidewallsis substantially closed.

The action of the oven anchorage, illustrated on the drawings, isessentially as follows:-

It may be assumed, that the arch is in cold condition, for instanceafter the erection, and therefore has the shape illustrated on the leftside of Figure 1, and that the springs of the easings l3 and I9, actingupon the tension rod l1, and the abutment levers l2 thus tightened sothat they will firmly hold arch in that position as indicated.

If the archis heated from the oven side, the individual arch bricks willexpand corresponding to the temperature drop existing in the arch rooffrom the oven side up to the upper side of the arch, and in accordancewith the coemcient of heat expansion of the brick material used. Theportion of the arch root of the ovens exposed to high temperaturesduring the heatingup may be preferably made out of magnesite .bricks orchromium magnesite bricks. The oven illustrated on the drawings forinstance is designed for the use of magnesite bricks.

With the unequal heating of the bricks, the brickwork of the arch notonly expands, u 1- the tension of the spring together bricks of themultaneously the radius of curvature and the angle of inclination at thecenter of the arch are changed. Consequently, the arch at operatingtemperature tends to alter itsshape, as illustrated on the right side ofFigure 1.

To ensure that the individual bricks of the roof arch are firmly heldtogether when the shape of the arch has been changed, the abutments l3must give way in such a manner, that they are swung outwardly until theyarrive at an angle, which corresponds to the altered angle ofinclination of the center of the arch.

The abutment plate l3 has to be arranged at such a distance frrom thepivotal bearing l3, for the lever l2 that the abutment in moving under34 and under the action of turning of the lever outwards or inwards, asthe case may be will perform that movement which corresponds to thealteration in the radius oi curvature and the change in elevation of thecenter of the oven arch. The right side of Figure 1 shows the abutmentplate l being moved in the correct manner, according to my invention.

To enable. the abutment Ill to move in the manner indicated, it will benecessary to control the tension of the springs 24, by a properadiustment of the set screws 23, in such a way that the levers will giveway outwards under the increased pressure resulting from the expansionof the arch under heat, the weight of the arch itself, however, beingfully taken up by the springs.

Furthermore, the springs 23 may be designed in such a manner, that theirtension at varying rates of compression will be equal to thecorresponding pressure of the arch roof.

Under certain circumstances, it may be advisable to arrange the abutmentplates ill for the conical rather than rectilinear arches not rigidlybut movably to the levers l2. Such a mode of carrying out my inventionis shown in Figures and 7.

Figure 5 shows the buckstays l of the anchorge, the oven side walls 3and the movable bricks 30 on the topmost layer oi! the side walls. Thearch shown has been marked with 3 and 3.

The end brick of the arch rests in a plate shaped abutment 3i. Theabutment plate 3| is provided with a lower projection 32, which preventsthe end brick of the arch from sliding from the abutment, said platehaving on the back a ball-shaped projection 33. The end 33 of the lever35 acts upon this ball-shaped projection 33, said lever being supportedpivotally at 33 in a bearing 31 provided on the buckstays 3. The springs33 placed between the end of the lever 33 and a pressure plate 33 arekept in position by a tension rod 40 and the nuts 4|, and act upon theupper end of the lever 33. The tension rod 43 is supported by means ofnuts 42 in a suitable manner at the vertical buckstays I.

The springs 33 and lever 33 do substantially the same work as theabutment levers and the springs according to Figure 1. The arch 3 isheld together by the force of the springs 33, which counteracts theweight of the arch, but the force or the springs gives way to theincreased arch pressure resulting from the heat expansion of the bricks.Due tothe fact, that the abutment lever 33 only acts loosely upon theball-shaped pro- ,iection 33 of the abutment plate 3|, the abutmentplate 3i can, moreover, perform a certain movement, relative to theabutment lever 34 in any desired direction. A screw 33 extends throughthe projection 33 and through a bore in the end of the lever 34, and thenuts 44 ensure a solid connection of the abutments 3| to the lever ends34, as soon as the arch has taken its final shape after the operatingtemperature has been arrived at.

A fixing of the abutment 3| is preferably done at this time, since witha free movement of the abutments of the arch, they may'tilt over whenthe temperatures are varying, thus causing certain tensions in the arch,by which the arch would collapse.

Instead of connecting the abutments by means of set screws rigidly tothe abutment levers, it is also possible to provide a yieldingconnection between the abutments and the abutment levers, whichconnection acts in such a way, that the abutments will partake of acertain movement relative to the abutment levers corresponding to theincreased pressure of the arch, without however giving way to the weightof the arch itself.

I have now described my present invention on the lines of a preferredembodiment thereof, but my invention is not limited in all its aspectsto the mode of carrying out as described and shown since the inventionmay be variously embodied ating heat, and

within the scope of the following claims.

I claim:-

1. A furnace roof for high temperature industrial furnaces comprising:an arched roof formed of individual refractory bricks arranged in an arcand suspended to span the furnace side walls freely thereof; abutmentsat the margins of the roof for supporting the bricks in contiguousrelationship with each other; and spring and lever mechanism mounted onan outside anchorage for the oven brickwork for yieldably clamping theabutments in clamping engagement with the bricks at the margins of theroof to clamp the bricks against each other and yet yield to accommodateexpansion. and contraction of the bricks under heat; and in which thebricks of the roof are free of suspensory means and otherwiseunsupported other than by their clamped contiguity with each other forfreedom of alteration of the shape, elevation and radius of curvature ofthe roof under expansion of operin which the spring and lever comprisesthe sole load carrying and supporting suspensory means for suspendingthe roof freely of the oven walls, with the levers mounted for movementin relation to the roof and designed and adapted for accommodatingthemselves to alteration in elevation as well as lineal movement of theroof as a result of alterations in radius of curvature of the roofduring expansion and contraction under operating heats; and with thesprings acting on the levers and designed and adapted to carry theentire weight of the roof as well as to adjust the levers to retractionand propulsion as the roof expands and contracts.

2. Apparatus as claimed in claim 1 and in which the levers comprisepivotally mounted upper and lower lever arms with the springsoperatively connected with the upper arms and the roof suspended fromthelower ends of the lower arms, and in which the pivotal axis is socormechanism also related, to the abutments as to cause the lower end ofthe lower arm to adjust itself to the alteration of the elevation of theroof arch as a whole during expansion and contraction of the roof archas a whole.

3. Apparatus as claimed in claim 1 and in which the levers comprisepivotally mounted upper and lower'lever arms with the springsoperatively connected with the upper arms and the roof suspended fromthe lower ends of the lower arms, and in which the pivotal axis is socorrelated to the abutments as to cause the lower end of the lower armto adjust itself to the alteration of the elevation of the roof arch asa whole during expansion and contraction of the roof arch as a whole andin which the spring mechanism comprises telescoping upper and lowercasing sections containing compressible inner springs and a connectingrod secured to the upper lever arm and extending through the easingsections and secured to the upper section, to draw the upper casingsection down thereby compressing the inner springs upon retraction ofthe lower arm by expansion of the roof against the lower arm, and to beurged upwardly by the inner springs and thus draw up the upper arm andpropel the lower arm towards the roof upon contraction thereof.

4. Apparatus as claimed in claim 1 and in which the clamping connectionbetween the levers and the abutments comprises a yieldable connectionpermitting relative movement between the abutments and their levers atthe juncture of the two to adjust them to each other during theirmovement under expansion and contraction of the roof are 5. Apparatus asclaimed in claim 1 and in which the connection between the abutments andtheir levers comprise a spherical projection on the abutment and acorrespondingly curved 00- operating socket on the lever, a screwextending through the spherical projection and through a bore in thelever and the socket for the spherical projection with the bore oflarger diameter than the screw and the screw fastened to the lever foradjustment of the spherical projection in the socket.

6. Apparatus as claimed in claim. 1 and in which the levers comprisepivotally mounted upper and lower lever arms with the springsoperatively connected with the upper arms and the roof suspended fromthe lower ends of the lower arms, and in which the pivotal axis is socorrelated to the abutments as to cause the lower end of the lower armto adjust itself to the alteration of the elevation of the roof arch asa whole during expansion and contraction of the roof arch as a whole andin which the spring mechanism comprises a volute spring encircling ahorizontal adjusting rod which extends through the upper arm of thelever and has a pressure plate with the volute spring compressible onthe rod between the pressure plate and the upper arm of the'lever.

WILLY UNDER.

